This invention relates generally to imaging and, more particularly, to image thickness selection for scalable multislice imaging systems.
In at least some imaging systems generally referred as computed tomography (CT) systems, an x-ray source projects a fan-shaped beam which is collimated to lie within an X-Y plane of a Cartesian coordinate system and generally referred to as the xe2x80x9cimaging planexe2x80x9d. The x-ray beam passes through the object being imaged, such as a patient. The beam, after being attenuated by the object, impinges upon an array of radiation detectors. The intensity of the attenuated beam radiation received at the detector array is dependent upon the attenuation of the x-ray beam by the object. Each detector element of the array produces a separate electrical signal that is a measurement of the beam attenuation at the detector location. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
In known third generation CT systems, the x-ray source and the detector array are rotated with a gantry within the imaging plane and around the object to be imaged so that the angle at which the x-ray beam intersects the object constantly changes. X-ray sources typically include x-ray tubes, which emit the x-ray beam at a focal spot. X-ray detectors typically include a collimator for collimating x-ray beams received at the detector, a scintillator adjacent the collimator, and photodiodes adjacent the scintillator.
In at least one known imaging system, the transmission profile collected from the detector represents a single slice of a patient. For single slice scanning, prospective and retrospective slice thicknesses are always identical. That is, only images having the slice thickness of the collected data may be generated. Therefore, in order to generate thin slice images, thin slice data must be collected. As result, large amounts of data must be stored for each image.
It would be desirable to provide a multislice CT system that can be used to collect one, two or more slices of data. It also would be desirable to provide such a multislice CT system that provides an operator with information related to available scan parameters so that the appropriate scan prescribed may be completed. In addition, it is desirable that the remaining scan parameters be updated based on prior scan parameter selections. Additionally, it is desirable that the configuration of the multislice system be automatically adjusted for the selected scan parameters.
In an exemplary embodiment a scalable multislice system includes a scalable multi-slice detector, a scalable data acquisition system (SDAS), scalable scan management, control, and image reconstruction processes, and scalable image user interface. As used herein, the term scalable generally means that an operator can readily and simply select the desired number of slices and the slice thickness for images to be displayed. The system enables the operator to select 1, 2, 4 or more slices to be displayed at a selected slice thickness. By enabling the system operator to make such selections, the image data for different clinical applications can be displayed in a most optimum format. No known multislice system provides an operator with such flexibility.
More specifically, and in an exemplary embodiment, the system includes a host computer coupled to a monitor for displaying images and messages to the operator. The host computer is coupled to a keyboard and a mouse to enable the operator to input information and commands to the host computer. The user interface is implemented using an instruction set stored in the host computer and enables the operator to select certain scan parameters including the desired number of slices and slice thickness. The host computer also is coupled to a scan and reconstruction control unit (SRU) which includes image generation controls.
A stationary controller is connected to the SRU, and the stationary controller is coupled to a table controller for controlling motion of the patient table. The stationary controller also is connected, through a slipring, to an on-board (i.e., on the gantry) controller and to a scalable data acquisition system (SDAS). The on-board controller controls operation of the x-ray source and operation of the SDAS, which converts analog signals from the scalable detector to digital data. The x-ray source includes a cam collimator controlled by the on-board controller. The position of the cams of the cam collimator are adjusted based on the desired number of slices and the desired slice thickness as defined by the operator using the user interface.
The system also includes a detector having a number (e.g., 57) of modules. Each module, in an exemplary embodiment, includes a scintillator array and a photodiode array. In the exemplary embodiment, the scintillator and photodiode arrays each are 16xc3x9716 arrays. The photodiodes are coupled to a switching apparatus which, in the one embodiment, includes an array of FETs, and the FETs control the combination of photodiode outputs based on the desired number of slices and slice thickness input the operator.
In operation, prior to performing a scan, the operator utilizes the user interface to prescribe certain scan parameters (e.g., a helical, axial, or cine scan, a table speed, and a pitch). After selection of each scan parameter, the options available for the remaining scan parameters are updated by the user interface. Based on the selections of the remaining scan parameters, the host computer, utilizing the user interface, presents the operator with prospective image thickness and retrospective image thickness options. Utilizing the displayed options, the operator may alter the prescribed scan parameters to achieve the desired prospective and retrospective image thicknesses. After confirming the selection, the prescribed scan parameters are used to configure system 10.
After transferring the configuration information to the appropriate elements of system 10, e.g., the detector, the SDAS, the collimator, as defined by the selected scan parameters, the prescribed scan is performed. More specifically, the photodiode outputs are supplied to the SDAS, via the FETs, for analog to digital conversion. The digital outputs from the SDAS are then supplied to the SRU via the slipring for image generation. Specifically, the SRU reconstructs images from the collected data, and such reconstructed images can be displayed to the user on the monitor or archived, or both. In addition, the operator may generate the available retrospective image thicknesses.
The above described scalable multislice system can be easily and simply operated to collect one, two, or more slices of data. Such system user interface provides the operator with available scan parameter options. In addition, the user interface updates the remaining scan parameters based on prior scan parameter selections. Additionally, the configuration of the multislice system is automatically adjusted for the selected scan parameters.